Metric Characterizations of Contextual Logic Programs

The aim of this paper is twofold: to characterize contextual logic programs by means of metric semantics and to argue the usefulness of metric characterizations for formally reasoning about program properties. A new denotational semantics of contextual logic programs is proposed. It is deened compositionally, without any help of any declarative paradigm and of any transition system. Following the lines of 7], it uses metric spaces rather than cpo's and processes as semantic domains. It is shown to be well-suited to tackle extra-logical features and abstract enough for program analysis. A methodology of program analysis is derived from the denotational metric charaterization of programs. It is suggested that most program properties can be proved by using the equalities deening the denotational semantics and by using inductive reasoning. Properties of the computed answer substitutions can also be established by reasoning about the substitutions reported by the semantics. Those claims are argued through the study of the universal termination property of several classical procedures .